Direct access storage devices (DASD) have become part of everyday life, and as such, expectations and demands continually increase for greater speed for manipulating and for holding larger amounts of data. To meet these demands for increased performance, the mechano-electrical assembly in a DASD device, specifically the Hard Disk Drive (HDD) has evolved to meet these demands.
Advances in magnetic recording heads as well as the disk media have allowed more data to be stored on a disk's recording surface. The ability of an HDD to access this data quickly and reliably is the result of steady progress in the engineering disciplines of materials research, electrical engineering, computer science and servo-mechanics. Furthermore, the success of HDDs is highly dependent on sophisticated manufacturing techniques.
A computer storage system may include a magnetic hard disk(s) or drive(s) within an outer housing or base containing a spindle motor assembly having a central drive hub that rotates the disk. An actuator includes a plurality of parallel actuator arms in the form of a comb that is movably or pivotally mounted to the base about a pivot assembly. A controller is also mounted to the base for selectively moving the comb of arms relative to the disk.
Each actuator arm has extending from it at least one cantilevered electrical lead suspension. A magnetic read/write transducer or head is mounted on a slider and secured to a flexure that is flexibly mounted to each suspension. The read/write heads magnetically read data from and/or magnetically write data to the disk. The head gimbal assembly (HGA) incorporates the head and the slider, mounted on the suspension. The slider is usually bonded to the end of the suspension.
A suspension has a spring-like quality, which biases or presses the air-bearing surface of the slider against the disk to cause the slider to fly at a precise distance from the disk with a large stiffness normal to the disk. Movement of the actuator by the controller causes the head gimbal assemblies to move along radial arcs across tracks on the disk until the heads settle on their set target tracks. The head gimbal assemblies operate in and move in unison with one another or use multiple independent actuators wherein the arms can move independently of one another.
Besides increasing the number of bits per inch stored along a track, increasing the number of tracks per inch allows more data to be stored on the surface of the disk. The number of data tracks recorded on the surface of the disk is determined partly by how well, in the presence of mechanical and electrical disturbances, the read/write head on the slider can be positioned and made stable over a desired data track.